1. Field of the Invention
The present invention relates to a ventilation system for a water tank which stores water to be used for moisturizing and cooling a fuel cell.
2. Description of Related Art
In a vehicle-mounted fuel cell system, hydrogen gas is supplied as a fuel gas to a hydrogen electrode of a fuel cell, and air is supplied as an oxidant gas and an air electrode of the fuel cell. These gases electrochemically react with each other to generate electric power.
Japanese Patent Application Laid-Open publications No. 2003-282106 and No. 2002-260708 disclose fuel cell systems having a water circulation system for moisturizing and cooling an electrolyte membrane, a fuel electrode, and an air electrode of a fuel cell.
Some hydrogen gas present in the fuel electrode of the fuel cell enters water passages of the water circulation system by a small amount. The water circulation system is connected to a water tank which stores pure water (hereinafter, water as appropriate). The hydrogen gas in the water passage is collected together with water and accumulated in the water tank, and is to be discharged to the outside through a ventilation system. Generally, the ventilation system sends air into the water tank for diluting the accumulated hydrogen gas therein, and discharges the diluted hydrogen gas to the outside through a discharge line.